In many electrical devices, apparatus and systems, electrical connectors are essentially used to enable circuit inter-connections and therefore to provide complete electrical power circuits. In many electrical applications, for example, electric vehicles, in which a high current supply is required, electrical connectors are used to provide sufficient current by connecting a plurality of current sources together in order to fulfil the current rating demands.
During the last two decades, the development of electrical vehicles has become an important research subject since electrical power vehicles are generally considered to be more environmental friendly then fossil fuel powered vehicles. Electric vehicles are generally powered by recyclable energy sources such as storage batteries, accumulators, or “super” capacitors which can be charged after each use. In order to provide adequate power to the driving motor, an electrical power source which can supply current in the rating of several hundred amperes is generally required for an electric vehicle. For example, the electrical power source may include a number of Nickel-Metal-Hydride or Nickel Cadmium batteries connected in series. Also, in order to provide adequate voltage level and current rating, battery cells or groups of batteries are generally interconnected by connectors having a low internal resistance.
The batteries, power capacitors, super-capacitors, accumulator cells, groups of batteries, accumulators or super-capacitors, are generally connected together by conductive metallic members made, for example, of copper, copper alloys, aluminium, aluminium alloys, nickel, nickel alloys, mild steel and like materials, in order to provide the necessary electrical power. For example, a common accumulator is formed by connecting a plurality of accumulator cells in parallel and/or in series and a corresponding number of electrical connectors are required to connect adjacent cells to form the accumulator.
The connectors are generally in the form of a metallic bar with a first and a second terminal ends and having a uniform thickness or cross-section between the terminals. The cross-sectional areas of the connectors are generally designed according to established rules of electrical engineering by reference to the rated current so that a rated current can flow through the connector continuously without generating excessive resistive heat.
The heat is generally due to the internal resistance of the connector and is generally proportional to the square of the current multiplied by the internal resistance. Since it is known that the internal resistance of a conductor is generally inversely proportional to its cross-sectional area for a given conductor, the use of conductors having a large cross-sectional area as connectors for high current applications to minimise heat dissipation would appear to be a natural solution. However, larger cross-sectional area means heavier and more costly connectors which are undesirable or even un-acceptable for many applications.
Furthermore, since good electrical connectors are usually also good thermal connectors, heat generated from other parts of the electric circuits, for example, from inside the battery or accumulator cells, will also be conducted to the connectors. Thus, the ability to dissipate unwanted heat becomes an important criteria for determining the performance of an electrical connector for high-current applications.
As mentioned earlier on, one of the typical connectors for high current applications includes a rigid metal bar having a first and a second terminal ends for connecting to the relevant electrical terminals. In fact, this type of rigid bar connectors is almost a standard choice for inter-battery cell connections. To mitigate fire and other hazards, it is always desirable to maintain the connectors below a safe temperature. Furthermore, excessive temperature will cause the rigid connector bar to expand which may cause distortion, or even damage, to the terminals or other components being connected.
Thus, it is desirable to provide an improved electrical connector which can be used in high-current as well as low-current applications and which will alleviate the heat dissipation problems associated with conventional electrical connectors. On the other hand, since a large number of connectors are usually used together in order to provide sufficient electrical power, the weight and cost of individual connector must be minimised since their adverse effects will be cumulative.
Hence, it will be advantageous if the improved connectors can substantially alleviate the short-comings associated with conventional high-current connectors while at the same time fulfilling the general requirements of being low in cost and weight, or at least, comparable to the cost and weight of conventional connectors.
It will be more advantageous if the improved connectors substantially fulfil the afore-said requirements and, at the same time, have a relatively compact and simple structure which at the same time provide improved heat dissipation characteristics and to slow down the building up of undesirable heat. In other words, it is advantageous to provide an improved electrical connector which is simple and has enhanced heat sinking, heat radiation or heat dissipation characteristics.
In view of the afore-said short-comings of conventional electrical connectors, it will be appreciated that there is a long-awaited and continuous need of improved electrical connectors which alleviate the short-comings associated with conventional connectors while generally fulfilling the afore-said requirements. In this regard, it is therefore desirable that the heat dissipation characteristics of an electrical connector of a certain cross-sectional area can be enhanced so that an improved electrical connector can be provided with no, or only minimal additional weight and cost overheads.